HD Broadcasting


you are placing a lot of emphasis on the assumptipn that general people notice such things.


How is it possible 7mate has a higher bitrate than 7HD? Does it mean both main channel and 7mate are in HD in Brisbane?


variable bitrates allow that to happen on occasion


I’d guess a longer term Cricket deal holds more weight for a network to do something vs the olympics passing through for a couple of weeks every few years

Plus Nine had Cricket in HD not everywhere of course and probably in less areas ever since WIN lost the affiliation deal


Also worth remembering that you’re comparing MPEG2 SD with MPEG4 HD, which seems to cope better with lower bitrates than the former


Seven finally launched their main channel in High Definition here in Darwin, took them a couple of years. Does it apply to all Southern Cross Seven broadcasting areas?


Definitely no upgrade for Central. I haven’t heard anything here about Spencer Gulf/Broken Hill.


Hard to believe so many parts of OZ didn’t have Seven in HD.

TV-NT have they dumped the SD version of 7 there as well, like they have in regional Queensland?


Doesn’t look like it.


Most regional WA, and Remote and Central sites build the mux as each site as they are fed from VAST. (The remainder are fed off-air from a nearby VAST fed site). Due to the nature of VAST, it transmits all of the channels in whatever configuration the satellite service requires, so can’t transmit a pre-build MUX, requiring each site to build a MUX itself. The distances between sites also make it impossible to have a main site with all other sites being fed off-air as is possible in the eastern states.

For all other areas, the MUX is built in the playout centre and sent to the main transmitter sites, with additional repeater sites being fed off-air.

How the stream is sent to the transmitter varies. WIN and Prime send use the Digital Distribution Australia (DDA - owned by WIN) network of point-to-point wireless links for most of their sites. SCA use fixed line (most likely still the Telstra DVN) to their local offices/studios and then use a wireless point-to-point link for the last “mile” to the transmitter site.
The metros, being larger markets with just one main site, as you’ve stated have more complicated backup paths with more duplication of equipment.

So they didn’t need to upgrade/replace/purchase any equipment. Plus, using MPEG-2 for HD also gives greater access as almost all TV’s currently in operation would be HD compatible for MPEG-2, but far less are MPEG-4 compatible.


Aha! And there’s why. 7HD in Darwin is in MPEG4 not MPEG2, unlike Queensland.


I just noticed on my TV that 7HD in Regional QLD is actually 1440x1080 as mentioned above.
Here’s the signal info from my TV


To me, 1440 isn’t really HD.

It’s Donald Trump like “fake” HD


How is it that a 1440x1080 footage can be shown in 16:9, from my calculations 1440x1080 should be 4:3 ?


SD is 720x576. Your TV is meant to see the ‘16:9 flag’ and stretch it to fit. From memory SBS HD MPEG-2 was 1440 and there was another network that did it too. Maybe WIN’s GEM?

It’s weird how 7 Qld is experiencing issues with this. WIN had similar problems when they converted 9Gem to SD. I can’t work out why it takes so long to rectify. Perhaps squeezing bandwidth results in some automatic correction which causes it.


Very interesting… seems like a dodgy way to broadcast a video signal, to expect the device receiving the signal to stretch it out.

Yeah, very weird. Given that 720x576 is the default for SD, is it possible that 7 QLD simply aren’t broadcasting any aspect ratio information with their signal, resulting in 7food Network coming through as 4:3?


Very possible. Just not sure of the reason. Like I said, it must be something they can only rectify by testing and tinkering over time. Suggests to me it’s bandwidth related or related to the balance of MPEG-2 and MPEG-4 services in one mux. Hopefully someone here can shed some light on it?


I was under the impression that - at least on DVB-T - all of the MPEG-2 HD signals had broadcast in 1440x1080i


Maybe in the beginning they did? It’s definitely a standard, but I remember people commenting on various forums that it was unusual that SBS was doing it.


SBS experimented with 1280x1080 for a brief period after switching from 720p, that caused a lot of receiver issues so they moved to the more standard 1440x1080 until they went MPEG4. The ABC also briefly - I think like a day or two - tried 960x720p on News 24, again lots of receivers didn’t like that.

Pretty much every network ran with 1440x1080 on their MPEG2 HD services, some changed that just prior to HD multichanneling to run at the full 1920x1080, but then I believe most if not all then changed back after launching SD multichannels to offset the bitrate cut that involved.